Does enzyme replacement therapy influence the ocular changes in type VI mucopolysaccharidosis?

Background: To describe the ocular changes noted in seven patients with type VI mucopolysaccharidosis (MPS VI) during 44 months of follow-up while on enzyme replacement therapy (ERT).

Methods: One male and six female patients with MPS VI were followed-up for a mean period of 44 months while undergoing enzyme replacement therapy (ERT) with recombinant arylsulfatase B (Naglazyme). They were examined annually for visual acuity, corneal clouding, intraocular pressure (IOP), optic nerve head and fundus morphology. Corneal clouding was documented by photography. We acknowledge that our methodology may not have been sensitive enough to detect extremely mild ocular changes, including minimal increases in corneal thickness or clouding. Nevertheless, this limitation has been considered in the interpretation of our findings.

Results: Ophthalmological findings remained stable in 5/7 patients. One patient experienced a modest improvement in visual acuity of more than 2 Snellen lines in one eye, while another patient suffered a deterioration in visual acuity of more than 2 Snellen lines in both eyes. Five out of seven patients showed optic nerve pathology: two of these exhibited optic nerve head swelling, while the other three showed variable degrees of optic nerve atrophy. All seven patients suffered from the typical corneal stromal opacities, however, to variable extents.

Conclusion: Visual function and ocular findings did not deteriorate in six out of seven MPS VI patients during a mean follow-up period of 3 and a half years on ERT.